Compositions and methods for degrading lignocellulosic biomass

Abstract

The present invention relates to compositions and methods of producing bioenergy products and metabolites of industrial interest from lignocellulosic biomass. More specifically, the invention describes the identification, characterization and isolation of novel bacteria having the remarkable ability to transform lignocellulosic biomass into fermentable sugars and, even more remarkably, into bioenergy products and metabolites. The invention also discloses a method to isolate such bacteria, compositions comprising such bacteria, and their uses for the modification of lignocellulosic biomass, with a view to producing bioenergy.

The invention claimed is: 
     
       1. A method of producing bioenergy products or metabolites, the method comprising exposing a lignocellulosic biomass to a bacterium to produce fermentable sugars, and fermenting said sugars into bioenergy products or metabolites, wherein said bacterium is selected from:
 a) a bacterium which can grow in the presence of lignin as a sole carbon source, at a temperature of at least 30° C., and resist 3 UV treatments of 4 mJ/cm 2  carried out at an interval of 4 hours; or 
 b) a bacterium which has the ability to utilize cellulose and xylan as carbon sources, at a temperature of at least 30° C., and to resist 3 UV treatments of 4 mJ/cm 2  carried out at an interval of 4 hours. 
 
     
     
       2. The method of  claim 1 , further comprising collecting said bioenergy products or metabolites. 
     
     
       3. The method of  claim 1 , wherein said bacterium can use lignin, cellulose and xylan as carbon sources. 
     
     
       4. The method of  claim 1 , wherein said bacterium can be cultivated in aerobic and anaerobic conditions. 
     
     
       5. The method of  claim 1 , wherein said bacterium belongs to a genus selected from  Deinococcus, Bacillus, Microbacterium, Cellulosimicrobium, Methylobacterium, Sphingobacterium, Pseudomonas, Caldimonas, Paenibacillus, Gordonia, Rhodococcus, Stenotrophomonas, Novosphingobium, Sphingomonas, Flavobacterium, Sphingobium, Sphingopyxis , or  Porphyrobacter.    
     
     
       6. The method of  claim 1 , wherein said bacterium is obtained by a method comprising:
 a) providing a sample comprising bacteria; 
 b) subjecting the sample to a cell-destructing UV irradiation comprising at least 3 UV treatments of 4 mJ/cm 2  carried out at an interval of 4 hours; and 
 c) culturing said UV treated sample in/on a selection medium containing: lignin as the sole carbon source, cellulose as the sole carbon source, xylan as the sole carbon source or a combination of cellulose and xylan as the sole carbon sources; and 
 d) isolating from said cultured UV treated sample, a bacterium which utilizes lignin as the sole carbon source in the selection medium, utilizes cellulose as the sole carbon source in the selection medium, utilizes xylan as the sole carbon source in the selection medium or utilizes both cellulose and xylan as sole carbon sources in the selection medium. 
 
     
     
       7. The method of  claim 1 , wherein the lignocellulosic biomass comprises unprocessed material of biological origin. 
     
     
       8. The method of  claim 7 , wherein the unprocessed material of biological origin is selected from forestry products, agricultural products, or aquatic products. 
     
     
       9. The method of  claim 1 , wherein the fermentable sugar is selected from glucose, cellobiose, mannose, xylose, arabinose or galactose. 
     
     
       10. The method of  claim 1 , wherein the bioenergy product is a biofuel. 
     
     
       11. A method of producing a biofuel, the method comprising exposing a lignocellulosic biomass to a bacterium to produce fermentable sugars, and fermenting said sugars into biofuel, wherein said bacterium is selected from:
 a) a bacterium which can grow in the presence of lignin as a sole carbon source, at a temperature of at least 30° C., and resist 3 UV treatments of 4 mJ/cm 2  carried out at an interval of 4 hours; 
 b) a bacterium which has the ability to utilize cellulose as a sole carbon source, at a temperature of at least 30° C., and to resist 3 UV treatments of 4 mJ/cm 2  carried out at an interval of 4 hours; 
 c) a bacterium which has the ability to utilize xylan as a sole carbon source, at a temperature of at least 30° C., and to resist 3 UV treatments of 4 mJ/cm 2  carried out at an interval of 4 hours; or 
 d) a bacterium which has the ability to utilize both cellulose and xylan as carbon sources, at a temperature of at least 30° C., and to resist 3 UV treatments of 4 mJ/cm 2  carried out at an interval of 4 hours.